Troubleshooting - Eggtimer Rocketry Eggtimer TRS Assembly Manual

Troubleshooting

If your Eggtimer TRS doesn't work after assembly and testing, take a deep breath, get out a
beverage to clear you mind, and start troubleshooting...
Check Your Solder Joints
The very first thing you should do is to check out all of the solder joints under a lighted
magnifier, and a 10x jeweler's loupe. The most common reason for things not working are
solder bridges, i.e. putting too much solder on the pads and shorting two adjacent pads
together. You can also get into problems by bridging pads with "vias" on the board, the
smaller holes that don't have any components soldered to them. This is especially true with
some of the pads around the resistors. Also, the pads on the GPS module are small, so you
want to make sure that you got just enough solder on them to bond the module to the pads.
Most of the holes and the pads are very small, so it doesn't take much solder to get a nice
"tented" solder joint. If you get a solder bridge, heat it up and use a solder wick or a vacuum
bulb to remove the excess; afterwards, we recommend resoldering the joints. Note: NEVER
use "canned air" or compressed air to "blow away" excess solder. The resulting splatter will
almost always cause more damage than the original solder bridge, and if you get solder splatter
on the RF module or inside the GPS module, there's no way to fix it.
Another thing to look out for is "cold" solder joints, they look dull and blobby compared to a
nice shiny "tented" solder joint. If you have a cold solder joint, it won't conduct well; at the
low power that the Eggtimer TRS uses this could easily keep things from working. If you have
a cold solder joint, heat it up and put just a little bit of solder on it, the main idea is to get a
little more flux on the joint. If there's too much solder, use a fine solder wick or a vacuum
bulb to remove the excess, then heat it up and resolder the joint.
Check Your Component Polarity
Most of the non-silicon components aren't polarized with the notable exception of the LEDs.
The long leads should have been inserted in the pad marked "+". Unfortunately, once you clip
the leads it may be difficult to tell if you have inserted it correctly. For example, if the amber
LED is backwards, you'll see the little red LED on the RF module blink, but the amber LED
will never come on.
If you inserted a component incorrectly, you will have to carefully unsolder it, clear any solder
residue from the holes, and resolder it. If you find that a component was soldered incorrectly,
you will have to use a vacuum bulb or vacuum desoldering tool to unsolder it. We cannot
stress enough that you need to check the orientation of the parts before you solder them. The
Eggtimer TRS Limited Warranty does not cover damage to a component while attempting to
unsolder it, so make take your time and make sure you get it right before you solder.